Hi all. I'm working on implementing a WiFi-controlled system on a dryer machine. I want to put a relay in series with the Start Switch of the dryer in order to enable/disable it, but I'm very hesitant about the current that flows through it, as I don't know if it'd be the full 30A the dryer operates with.

The Start Switch model is: WPW10420741
The dryer machine model is: YNED4655EW1

The idea of the project is to control the use of the machine in a rental property. Tenants will use an RFID card, the RFID reader is connected to an ESP32, which sends the data through WiFi to a remote server that validates the data, then the data enables the relay which enables the current to flow into the dryer machine for a determined period of time.

I mainly want to know the current rating of the Start Switch, which I couldn't find anywhere. But any suggestions or tips are more than welcomed. I just graduated as an electronics technologist and this is my first home project of IoT. Thanks!

 

You could probably interrupt the control rather than the whole load. Post a schematic.

 

The Start Switch model is: WPW10420741 look here switch supplier

The wiring diagram is not readily available many dryers do not use a control circuit. Everything is direct switched. Hence the supplier photo indicated switch rating 125-250V at 15 Amps. A cross check on parts suppliers shows the door switch is rated at 11 Amps. So it leans toward all direct switched circuits. Without an actual diagram to confirm the circuit it would be prudent to use a control relay with contact rating of 15 Amps.

 

I think your 15A relay would work fine. I'm guessing that the end user would still use the push button start switch once the relay is energized, so the relay isn't really opening or closing the circuit, just enabling the Start circuit which is generally the start winding of the motor and maybe a relay to control the heat coils, but not them directly. Once the motor starts and you release the start switch, that circuit is open and no current flow is through the switch anyway. Should work I would think. Good luck.

 

Here is a typical whirlpool dryer

 

Good info Max, and as I mentioned, the start switch just gets the motor running and then is no longer used until the next Start requirement. The relay in the OP question could or would be just like the door switch or if he'd rather connect in series with the start switch directly that would work also. Thanks for posting the schematic, can't get much simpler than that... OK, a close line maybe, but...

 

This is an old Whirlpool switch number The switch rating is 15A and only controls the 120 V drum motor and blower fan. The heat is controlled by a separate 30A relay whose coil
gets power from the control board. Theoretically, You would l need two relays for this task. One to interrupt power in series with the switch to inhibit power ad alsoto turn the dryer
off, and another momentary one in parallel with this switch to turn the dryer on.
I am not recommending that you do this, since it could be unsafe to do and you could be liable in the event of a mishap not to mention voiding your insurances if it does since it
would be their excuse not to have to pay a claim. Modifications usually voids any manufacturer warranties also. I would also worry about potential fire from an unclean lint filter
should the tenants neglect to clean it each time it is used.